knitr does not compile pdf - r

Question

I'm new to coding and I`m trying to use knitr to print a PDF. I have installed R 3.5.3 and RStudio installed correctly as simple codes usually run.
I have both installed in the same folder as Miktex 2.9.7
As I create a new markdown file with a PDF output, incoded in UTF-8, I get the standard model text.
I've tried different encodings and reinstalled miktex several times.
When I run a code I used at my uni lab, it runs, but if I alter even 1 character on a string and save it, it wont compile the pdf anymore.
This is what I've been trying to compile:
---
title: "Lista 1"
date: "April 6, 2019"
output: pdf_document
---
```{r instalar pacotes necessarios}
# Carregando os pacotes necessários
if (!require("pacman")) install.packages("pacman")
pacman::p_load("tinytex", "tidyverse")
```
Questão 1
Use os conhecimentos adquiridos em sala de aula (e fora dela!) para realizar >as seguintes operações sobre o
banco de dados mpg:
```{r variaveis q1a}
posicao <- 100
item.a <- mpg[posicao, c("manufacturer","model")]
```
a) A partir do código acima podemos verificar que o veículo de posição `r posicao` banco de daados é um `r item.a`
```{r}
media.milhas.cidade <- mean(mpg$cty)
```
b) A partir do código acima, pode-se verificar que a média de milhas por galão na cidade é `r media.milhas.cidade`
I should just get the pdf but Rstudio prints this:
================================
processing file: lista1mkd.Rmd
|......... | 14%
ordinary text without R code
|................... | 29%
label: instalar pacotes necessarios
|............................ | 43%
ordinary text without R code
|..................................... | 57%
label: variaveis q1a
|.............................................. | 71%
inline R code fragments
# A tibble: 1 x 2
manufacturer model
<chr> <chr>
1 honda civic
|........................................................ | 86%
label: unnamed-chunk-1
|.................................................................| 100%
inline R code fragments
"C:/Program Files/RStudio/bin/pandoc/pandoc" +RTS -K512m -RTS lista1mkd.utf8.md --to latex --from markdown+autolink_bare_uris+ascii_identifiers+tex_math_single_backslash --output lista1mkd.tex --template "C:\Users\CESARA~1\DOCUME~1\R\WIN-LI~1\3.5\RMARKD~1\rmd\latex\DEFAUL~3.TEX" --highlight-style tango --latex-engine pdflatex --variable graphics=yes --variable "geometry:margin=1in" --variable "compact-title:yes"
output file: lista1mkd.knit.md
Error: Failed to compile lista1mkd.tex. See https://yihui.name/tinytex/r/#debugging for debugging tips.
In addition: Warning message:
In readLines(logfile) : incomplete final line found on 'lista1mkd.log'
Execution halted